[fix] pyright repported errors

The errors make pyright usage useless since a new error won't be seen [1].

[1] https://github.com/searxng/searxng/pull/1569

```
  searx/compat.py:11:27 - error: Expression of type "Type[cached_property[_T@cached_property]]" cannot be assigned to declared type "Type[cached_property]"
    "Type[cached_property[_T@cached_property]]" is incompatible with "Type[cached_property]"
    Type "Type[cached_property[_T@cached_property]]" cannot be assigned to type "Type[cached_property]" (reportGeneralTypeIssues)
  searx/utils.py:69:36 - error: Expression of type "None" cannot be assigned to parameter of type "str"
    Type "None" cannot be assigned to type "str" (reportGeneralTypeIssues)
  searx/utils.py:573:85 - error: Expression of type "None" cannot be assigned to parameter of type "int"
    Type "None" cannot be assigned to type "int" (reportGeneralTypeIssues)
  searx/webapp.py:1306:22 - error: Argument of type "str" cannot be assigned to parameter "__a" of type "BytesPath" in function "join"
    Type "str" cannot be assigned to type "BytesPath"
      "str" is incompatible with "bytes"
      "str" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:68 - error: Argument of type "Literal['themes']" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "Literal['themes']" cannot be assigned to type "BytesPath"
      "Literal['themes']" is incompatible with "bytes"
      "Literal['themes']" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:78 - error: Argument of type "str | Any | None" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "str | Any | None" cannot be assigned to type "BytesPath"
      Type "str" cannot be assigned to type "BytesPath"
        "str" is incompatible with "bytes"
        "str" is incompatible with protocol "PathLike[bytes]"
          "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:85 - error: Argument of type "Literal['img']" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "Literal['img']" cannot be assigned to type "BytesPath"
      "Literal['img']" is incompatible with "bytes"
      "Literal['img']" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/engines/mongodb.py:8:6 - warning: Import "pymongo" could not be resolved (reportMissingImports)
  searx/engines/mysql_server.py:9:8 - warning: Import "mysql.connector" could not be resolved (reportMissingImports)
  searx/engines/postgresql.py:9:8 - warning: Import "psycopg2" could not be resolved from source (reportMissingModuleSource)
  searx/engines/xpath.py:187:28 - warning: "categories" is not defined (reportUndefinedVariable)
  searx/search/__init__.py:184:82 - warning: "flask" is not defined (reportUndefinedVariable)
  searx/search/checker/background.py:19:26 - error: Type of "schedule" is partially unknown
    Type of "schedule" is "(delay: Any, func: Any, *args: Any) -> Literal[True]" (reportUnknownVariableType)
  searx/shared/__init__.py:8:12 - warning: Import "uwsgi" could not be resolved (reportMissingImports)
  searx/shared/shared_uwsgi.py:5:8 - warning: Import "uwsgi" could not be resolved (reportMissingImports)
```

1 files changed, 2 insertions, 1 deletions

diff --git a/manage b/manage
index f7cada3e1..c887826e2 100755
--- a/manage
+++ b/manage
@@ -698,7 +698,8 @@ test.pyright() {
         | grep -v '/engines/.*.py.* - warning: "logger" is not defined'\
         | grep -v '/plugins/.*.py.* - error: "logger" is not defined'\
         | grep -v '/engines/.*.py.* - warning: "supported_languages" is not defined' \
-        | grep -v '/engines/.*.py.* - warning: "language_aliases" is not defined'
+        | grep -v '/engines/.*.py.* - warning: "language_aliases" is not defined' \
+        | grep -v '/engines/.*.py.* - warning: "categories" is not defined'
     dump_return $?
 }